diff --git a/src/LaTeXFeatures.C b/src/LaTeXFeatures.C
index cb28134d43..01049c315e 100644
--- a/src/LaTeXFeatures.C
+++ b/src/LaTeXFeatures.C
@@ -339,15 +339,19 @@ string const LaTeXFeatures::getTClassPreamble() const
 	// the text class specific preamble 
 	LyXTextClass const & tclass = textclasslist.TextClass(params.textclass);
 	ostringstream tcpreamble;
-	
+
 	tcpreamble << tclass.preamble();
 
 	for (layout_type i = 0; i < tclass.numLayouts(); ++i) {
 		if (layout[i]) {
-			tcpreamble  << tclass[i].preamble();
+			tcpreamble << tclass[i].preamble();
 		}
 	}
 
+	// DEC's implementation of ostringstream has a bug which can be
+	// overcome with this forcing.
+	tcpreamble.seekp(std::ios::beg);
+
 	return tcpreamble.str().c_str();
 }	
 
diff --git a/src/frontends/xforms/ChangeLog b/src/frontends/xforms/ChangeLog
index 590d44a465..03781d585d 100644
--- a/src/frontends/xforms/ChangeLog
+++ b/src/frontends/xforms/ChangeLog
@@ -8,6 +8,13 @@
 	* xforms-helpers.h: added two choice const for the LyXLength
 	one with all and one only with length which have a unit.
 
+2002-01-29  Jürgen Spitzmüller  <j.spitzmueller@gmx.de>
+
+	* forms/form_minipage.fd: add text_warning field.
+
+	*FormMinipage.[Ch]: added input filters and warnings
+	(ButtonPolicy::SMInput FormMinipage::input)
+
 2002-01-28  Angus Leeming  <a.leeming@ic.ac.uk>
 
 	* FormAboutlyx.[Ch]: Removed redundant form() method and
diff --git a/src/frontends/xforms/FormMinipage.C b/src/frontends/xforms/FormMinipage.C
index 4e9ec3a126..519f3c4559 100644
--- a/src/frontends/xforms/FormMinipage.C
+++ b/src/frontends/xforms/FormMinipage.C
@@ -90,3 +90,28 @@ void FormMinipage::update()
 	break;
     }
 }
+
+ButtonPolicy::SMInput FormMinipage::input(FL_OBJECT * ob, long)
+{
+	ButtonPolicy::SMInput action = ButtonPolicy::SMI_NOOP;
+
+	// disallow senseless data
+	// warnings if input is senseless
+	//
+	string input = fl_get_input(dialog_->input_width);
+	bool invalid = false;
+
+	if (ob == dialog_->input_width) {
+		invalid = !isValidLength(input) && !isStrDbl(input);
+		if (invalid) {
+			fl_set_object_label(dialog_->text_warning,
+				_("Warning: Invalid Length!"));
+			fl_show_object(dialog_->text_warning);
+			action = ButtonPolicy::SMI_INVALID;
+		} else {
+			fl_hide_object(dialog_->text_warning);
+			action = ButtonPolicy::SMI_VALID;
+		}
+	}
+	return action;
+}
diff --git a/src/frontends/xforms/FormMinipage.h b/src/frontends/xforms/FormMinipage.h
index d640f50614..deaaa0eb2c 100644
--- a/src/frontends/xforms/FormMinipage.h
+++ b/src/frontends/xforms/FormMinipage.h
@@ -39,6 +39,8 @@ private:
 	virtual void build();
 	/// Update dialog before/whilst showing it.
 	virtual void update();
+	/// Filter the inputs on callback from xforms
+	virtual ButtonPolicy::SMInput input(FL_OBJECT *, long);
 
 	/// Fdesign generated method
 	FD_form_minipage * build_minipage();
diff --git a/src/frontends/xforms/form_minipage.C b/src/frontends/xforms/form_minipage.C
index 81ec868406..427dbdcfcf 100644
--- a/src/frontends/xforms/form_minipage.C
+++ b/src/frontends/xforms/form_minipage.C
@@ -89,6 +89,8 @@ FD_form_minipage * FormMinipage::build_minipage()
   }
     fl_set_object_lsize(obj, FL_NORMAL_SIZE);
     fl_set_object_callback(obj, C_FormBaseRestoreCB, 0);
+  fdui->text_warning = obj = fl_add_text(FL_NORMAL_TEXT, 20, 90, 210, 30, "");
+    fl_set_object_lalign(obj, FL_ALIGN_LEFT|FL_ALIGN_INSIDE);
   fl_end_form();
 
   fdui->form->fdui = fdui;
diff --git a/src/frontends/xforms/form_minipage.h b/src/frontends/xforms/form_minipage.h
index 9598da08ca..a7f45190a3 100644
--- a/src/frontends/xforms/form_minipage.h
+++ b/src/frontends/xforms/form_minipage.h
@@ -27,6 +27,7 @@ struct FD_form_minipage {
 	FL_OBJECT *button_apply;
 	FL_OBJECT *button_ok;
 	FL_OBJECT *button_restore;
+	FL_OBJECT *text_warning;
 };
 
 #endif /* FD_form_minipage_h_ */
diff --git a/src/frontends/xforms/forms/form_minipage.fd b/src/frontends/xforms/forms/form_minipage.fd
index 2b610ab11b..962b3f8e98 100644
--- a/src/frontends/xforms/forms/form_minipage.fd
+++ b/src/frontends/xforms/forms/form_minipage.fd
@@ -10,7 +10,7 @@ Unit of measure: FL_COORD_PIXEL
 Name: form_minipage
 Width: 430
 Height: 170
-Number of Objects: 14
+Number of Objects: 15
 
 --------------------
 class: FL_BOX
@@ -105,7 +105,7 @@ argument: 0
 --------------------
 class: FL_BEGIN_GROUP
 type: 0
-box: 0 10 10 0
+box: 0 0 0 0
 boxtype: FL_NO_BOX
 colors: FL_COL1 FL_MCOL
 alignment: FL_ALIGN_CENTER
@@ -264,5 +264,23 @@ name: button_restore
 callback: C_FormBaseRestoreCB
 argument: 0
 
+--------------------
+class: FL_TEXT
+type: NORMAL_TEXT
+box: 20 90 210 30
+boxtype: FL_FLAT_BOX
+colors: FL_COL1 FL_MCOL
+alignment: FL_ALIGN_LEFT|FL_ALIGN_INSIDE
+style: FL_NORMAL_STYLE
+size: FL_DEFAULT_SIZE
+lcol: FL_BLACK
+label: 
+shortcut: 
+resize: FL_RESIZE_ALL
+gravity: FL_NoGravity FL_NoGravity
+name: text_warning
+callback: 
+argument: 
+
 ==============================
 create_the_forms